Sheet separating apparatus

ABSTRACT

Apparatus for feeding single sheets of sheet material from a stack including nonresilient friction roller means which cooperate with the penultimate and lower adjacent sheets to inhibit movement thereof while the top sheet is being withdrawn from the stack.

United States Patent John Taini Skokie, Ill.

App]. No 757,859

Filed Sept. 6, 1968 Patented Jan. 19, 1971 Assignee Bell & Howell Company Chicago, III.

a corporation of Illinois Inventor SHEET SEPARATING APPARATUS 3 Claims, 4 Drawing Figs.

U.S. CI 271/36 Int. Cl 865g 65/28 Field ofSearch 271/36, 10, 4; 221/43 References Cited UNITED STATES PATENTS 8/1941 Morrison et al. 8/1944 Morse 4/1955 La Bombard... 5/1959 Tobey FOREIGN PATENTS 3/1957 Great Britain Primary Examiner-Even C. Blunk Assistant ExaminerDouglas D. Watts Attorney.lack H. Hall ABSTRACT: Apparatus for feeding single sheets of sheet material from a stack including nonresilient friction roller means which cooperate with the penultimate and lower adjacent sheets to inhibit movement thereof while the top sheet is being withdrawn from the stack.

SHEET SEPARATING. APPARATUS DISCLOSURE This invention relates in general to apparatus for serially feeding sheet material from a superimposed stack such as may be used in conjunction with apparatus for reproducing visual matter. In particular, this invention relates to apparatus for separating said sheet material from said stack to thereby enable feeding of only one sheet from said stack per operational cycle of the reproducing apparatus.

A vexatious problem in copying and duplicating devices wherein the copying medium comprises precut sheet material positioned in superimposed stacked relationship, is to insure repetitive feeding of single copy sheets from the supply stack to the sheet transport means of the reproduction apparatus. Multiple feeds, that is, withdrawing two or more sheets from the stack per operational cycle, are extremely detrimental from a standpoint of waste, inefficiency and poor copying results.

Multiple sheet feeds usually occurred due to surface friction between adjacent copy sheets. The surface friction is difficult to overcome regardless of the direction in which the sheets are being fed, but it is especially difficult to overcome when the feed direction is parallel to the plane of the sheet surface and when movement'of the sheet is accomplished by frictional engagement with the exposed surface of the uppermost sheet of the stack, since of necessity, the frictional engagement also requires a downward force upon the surface of the uppermost sheet and a resultant normal friction force component between the opposing surfaces of the-top sheet and thepenultimate sheet.

In low .and moderately priced reproduction equipment, sheet separation is typicallyeffected by causing buckling between the uppermost and adjacent sheets. Buckling produces an air gap or space between the adjacent sheets which reduces the surface friction and substantially eliminates the tendency for one sheet to be dragged along with another sheet. Buckling devices employed for sheet separation have been found to be unreliable and undesirable due to possible damage to the leading edge of the copy sheet whereat the buckling devices usually operate, since for effective separation the buckling maybe substantially sever.

This invention obviates the difficulties involved in preventing multiple sheet feeds and effecting reliable sheet separation by providing means for inhibiting movement of the penultimate and lower adjacent sheets of the superimposed stack. By allowing movement of only the top sheet, the sheet which is actually being fed, and simultaneously inhibiting movement of the penultimate and lower adjacent sheets, fortuitous withdrawal of other than the top sheet is prevented.

In accordance with the invention, spring loaded rollers having abrasive surfaces exhibiting a high coefficient of friction are provided adjacent each lateral edge of the stacked copy sheets. The rollers are biased into contact with the edges of the stack and are inclined toward each other at their upper ends. Thus, frictional contact between the roller peripheral surfaces and the stack edge only occurs at and adjacent the top of the stack and movement of only the penultimate and lower adjacent sheets is inhibited during withdrawal of the top sheet.

The rollers remain stationary during withdrawal of each sheet from the superimposed stack but are mounted on the feed shelf for rotation about an axis. Upon placement of a fresh stack of copy paper onto the feed shelf, the friction between the roller surfaces and the stack causes rotation and presents fresh abrasive surfaces to the lateral edge. Also, the friction rollers are mounted on the feed shelf for quick removal and for facilitating eachrenewal of the peripheral friction surface.

Accordingly, the primary object of this invention is to provide means for separating sheet material fed from a superimposed stack.

Another object of this invention is to provide means for separating sheet material fed singly from a superimposed stack comprising means for inhibiting movement of the penultimate and lower adjacent sheets of the stack while the top sheet is withdrawn.

An additional object of this invention is to provide friction those versed in the art upon an understanding of the following detailed description taken in conjunction with the accompanying drawings in which a preferred embodiment of the sheet feeding apparatus is shown and wherein:

FIG. 1 is an isometric view of a'copying machine incorporating the principles of the sheet separator of the invention.

FIG. 2 is a top plan view of the feed shelf and sheet separator of the invention without a superimposed stack of sheet material thereon.

FIG. 3 is a cross-sectional elevational view of the sheet separating apparatus of the invention taken along offset section line 3-3 of FIG. 2 but with a stack of superimposed sheet material on feed shelf. A separating roller is shown in exploded detail.

F IG. 4 is a transverse cross-sectional elevational view of the sheet separation apparatus taken along line 4-4 of FIG. 2, also illustrating a stack of superimposed sheet material on the feed shelf.

Referring now to FIG. 1 of the drawings, an electrostatic. copying machine 10 is shown and is seen to include a centrally located copy paper feeding station 12 which is normally concealed'by a lid, not shown. Sheets of copy paper are fed from thefeed station responsive to insertion of an original document into the machine at an entrance 14.

Referring now to FIGS. 2 and 3, the sheet feeding and separating apparatus generally comprises a horizontal shelf 16 for supporting a stack of superimposed copy sheet material 18 in proper position for being fed by sheet feeding means 20 into the nip formed by a pair of transport rollers 21 and 22 interior of the electrostatic copier. From the transport rollers, the copy sheet is directed through various stations wherein a coat ing on the sheet surface may be sequentially electrostatically charged, exposed to an image of the original document and developed to produce a resultant image on the copy sheet. Sheet feeding means 20 withdraws individual sheets from the top of the stack and the uppermost sheets thereof are retained and prevented from being drawn along with the top sheet by biased friction sheet restraining means 24 disposed on each side of the stack.

Shelf 16 comprises a fixed rear shelf member 26 and a pair of laterally movable front shelf members 28 and 30, each of said shelf members resting on a bottom wall 31 of the paper feeding station. The shelf members cooperate to provide a flat planer surface for supporting the stacked copy sheets. Fixed rear shelf member 26 defines a pair of generally V-shaped slots 32 at each side thereof. Each slot is adapted to receive a guide post 34 which may be loosened by a thumbscrew 36 at the upper end thereof for movement along the slot to accommodate copy sheets of varying lengths and widths, and which may be subsequently tightened to position and guide the stacked sheets.

Each front shelf member 28 and 30 includes a vertically upstanding, planar sheet guide 38 which contacts the lateral contacts the lateral edges of the stack, adjacent the leading edge thereof, as will be noted in detail hereinafter. Each front shelf center of the feed shelf and cooperates with a stationary transverse angle rail 44 of the copying machine. The angle rail defines a longitudinal slot 46 for each support arm. Slot 46 receives a'stabilizing stud 50 staked to member 42 and also accommodates a locking thumbscrew 52 which passes through member 42 and the rail. Cooperation between the thumbscrew and slot allows lateral adjustment of each of the front shelf members and each of the attached side guides 38 for assisting in accommodating copy sheets of varying widths. If desired, indicia markings 53 (See FIG. 4) corresponding to standard widths which the copy sheets may assume may be stamped on rail 44. A reference line 55 provided on lateral extension 42 may be lined up with the indicia markings to provide quick reference for setting the lateral distance between the guides.

Sheet feeding means comprise a transverse drive shaft 60 overlaying the copy paper stack which is cyclically driven durmg each copying operation by motor means interiorly of the machine 10, not shown. The shaft is mounted in bearings 62 and 64 at each side of the copy paper compartment and supports a pair of sloping feed arms 66 and 68 which are secured for movement relative to the shaft by nylon bearings 70 so that rotation of the shaft is not communicated to the feed arms. The nylon bearings also allow the feed arms to be lifted from the surface of stack 18 for replacement of sheet material upon depletion thereof and enables the feed arms to ride the stack as the sheet level is reduced. Feed arms 66 carry a transverse shaft 72 at their lower ends which is disposed parallel to the surface of the copy sheets and slightly thereabove.

Shaft 72 carries a pair of self rubber driving wheels 74 which rest directly upon the top sheet of stack 18 and frictionally contact its top surface. The driving wheels are secured to shaft 72 by means of C-clips 76 on each side thereof and include one-way clutches, not shown, which enable the driving wheels to drive the top sheet in only one direction. Shafts 60 and 72 are coupled by a ribbed flexible belt 78 trained over a gear 80 staked to shaft 60 and a gear 82 staked to shaft 72. Thus, with rubber drive wheels 74 resting on the top of stack 18, clockwise rotational movement of shaft 60, as viewed in H0. 3, will produce clockwise rotation of the drive wheels and cause forward movement of the top sheet toward the transport rollers 2l-22. The top sheet is guided into the nip formed by the' transport rollers by a pair of converging paper guides 84 and 86.

Desirably, this forward movement of the top sheet by the friction drive wheels will cause withdrawal of only one sheet from the stack, although as is well known by those familiar with the art, surface friction between adjacent sheets often causes withdrawal of multiple sheets from the stack, Thus, in accordance with the invention, sheet restraining means 24 are provided outwardly but adjacent each front shelf member 28 and 30. The sheet restraining means are housed in a pair of unitary enclosures-86 86 formed integral with each from shelf memberand comprising a lateral side wall 88, a front wall 89, a rear wall 90, a top wall 91, and a bottom wall 92. The enclosure is open at 93, opposite wall 88, and is exposed to a lateral edge of the stack of copy paper thereat as will be note hereinafter.

, Each enclosure contains a pair of friction rollers 95-95 which are mounted for free rotation therein by a permanent lower bearing pin 96 received in a laterally elongated slot 98 formed in bottom wall 92, and a removable upper bearing pin 100 received in a laterally elongated slot 102 formed in upper wall 91. Each roller is independent of its adjacent roller and is also independent of each roller at the opposite side of the machine.

The rollers are cylindrically shaped and each pair is biased against a side edge of stack 18 by a beryllium-copper spring 104 having a generally flat cross section and having an apex 106 in supporting contact with the inner surface of wall 88 and having an upper arcuate end 108 and a lower arcuate end 110 in contact with the peripheral surfaces of rollers 95. The distance between lower end 110 and the apex 106 is about one-third the total distance between lower end 110 and upper end 108.

Slots 102 and 98 through upper wall 91 and lower wall 92, respectively, are not in exact vertical alignment. More particularly, the limits of upper slot 102 extend closer to the-stack than do the limits of lower slot 98 which causes each roller to assume'an inclined attitude towardtheedge of the stack such that the distance between the upper ends of the rollers is less that the distance between the lowerends thereof. in this "attitude, best seen in H6. 4, the rollers only cooperate with the uppermost sheets of the stack to inhibit movement thereof upon withdrawal of the top sheet by'the copy feed means.

Each roller is substantially non resilie'ntand as best seen in the exploded view in FIG. 3, comprises acylindrically shaped core 110 with pin 96 permanently secured to and depending therefrom. A'hollowsleeve 1 12 is-adapted'to be received by core 110. The sleeve is fabricated of cardboard or similar rigid material and includesan abrasive, sandpaperlike coating onits exterior peripheral surface which, as is well known, exhibits a high coefficient of friction. The frictional surface establishes a firm frictional engagement with the lateral edges of the superimposed stack of sheet material for inhibiting movement thereof upon withdrawal of the top sheet from the stack.

The slight inclination of the roller causesa firm engagement between the abrasive surface and top sheet, the penultimate sheet, and the lower'adjacent sheets of the' stack. The firm engagement causes a sufficiently large frictional force between the roller surface and thepenultimate and lower adjacent sheets of the stack to prevent rotation of the roller during withdrawal of the top sheet. Thus, during normal operation of the copying machine, each of the rollers 95 is stationary arid each successive'top sheet of the stack is drawn therepast while movement of the penultimate and lower adjacentsheets is inhibited. I

Withdrawal of successive top sheets'past the-abrasive roller surface eventually causes clogging thereof and'reduces its frictional effectiveness, thus it is desirable to expose a fresh abrasive surface each time the stack is renewed.

When a fresh stack 18 of sheet'material is loaded onto shelf 16, the stack must. necessarily be slid forward under feed means 20. This forward movement of the entire stack at one time and the frictional contact between the edges of the stack and the rollers, cause a rotational movement to be imparted thereto which presents a fresh abrasive surface to the lateral edges of the stack. I

The rollers are removably retained in enclosures 86 by the top pin which is received ina'blind bore 114 through the center of core 110. By removing pin 100 when the supply of sheet material has been expended, the core and sleeve may be removed from the enclosure. The 'old sleeve may then be discarded anda new sleeve substituted therefore, after which the rollers may be reinserted into their enclosures'byrepositioning them and reinserting pin 100. This is a simple-service procedure and due to the low cost of the abrasive sleeves, may be accomplished'as partoffthe routine service maintenance.

it is obvious thatupon study by those skilled-in the art the disclosed invention'may bealteredbr modified both in physicalappearance and construction without'dep'arting from its inventive concept. Therefor, the scope of protection to be given this invention should not be limited by the embodiment described above, but'should be determined by the essential descriptions thereof which-appear in the appended claims.

I claim:

1. Apparatus for separating sheet material fed from a superimposes stack comprising: I v

shelf means supporting said stacked sheet material;

means engaging the top sheet of said stacked material and imparting movementthereto parallel 'to the plane of said sheets for displacing it from said stack;

a plurality of cylindrical members disposed and supported for rotation on opposite sides of said stack parallel to the direction of sheet displacement and each in contact with one edge of said stacked sheet material and frictionally cooperating with said stack for inhibiting movement of the penultimate and lower adjacent sheets; each of said members including a peripheral friction surface oriented generally parallel to the edge of said stacked sheet material supported for rotation about a generally vertical axis; I

means biasing said members into firm contact with only the uppermost sheets of said stack for inhibiting movement of only said uppermost sheets;

said peripheral friction surface comprising an abrasive coating wherein the coefficient of friction between said coating and said top sheet is substantially less than the total coefficient of friction between said coating and said penultimate and lower adjacent sheets whereby said cylindrical member remains stationary during displacement of said top sheet from said stack;

and wherein each of said cylindrical members are mounted for quick removability from said support for periodic renewal of its abrasive surface.

2. The sheet separating apparatus as set forth in claim l6 wherein each of said cylindrical members comprise a cylindrical core receiving a low cost abrasive coated sleeve which may be discarded and replaced for renewal of said abrasive surface.

3. In combination with apparatus for reproducing visual subject matter on sheet material and having sheet transport means, sheet feeding and separating means for delivering sin- 5 gle sheets to said reproducing apparatus comprising:

a substantially horizontal shelf supporting a stack of superimposed sheet material adjacent said transport means;

sheet movement means disposed above said stack and engaging the top sheet .thereof for horizontally displacing said top sheet from said stack and directing it to said transport means;

a plurality of normally stationary, cylindrically shaped members having abrasive coatings on the periphery thereof cooperating with the upper portion of said stack for inhibiting movement of the penultimate and lower adjacent sheets during displacement of said topsheet;

said cylindrical members comprising an easily removable inner core and an outer abrasive sleeve received by said core;

said outer abrasive sleeve being readily removable from said core to facilitate replacement thereof upon the abrasive surface being clogged with said sheet material. 

1. Apparatus for separating sheet material fed from a superimposes stack comprising: shelf means supporting said stacked sheet material; means engaging the top sheet of said stacked material and imparting movement thereto parallel to the plane of said sheets for displacing it from said stack; a plurality of cylindrical members disposed and supported for rotation on opposite sides of said stack parallel to the direction of sheet displacement and each in contact with one edge of said stacked sheet material and frictionally cooperating with said stack for inhibiting movement of the penultimate and lower adjacent sheets; each of said members including a peripheral friction surface oriented generally parallel to the edge of said stacked sheet material supported for rotation about a generally vertical axis; means biasing said members into firm contact with only the uppermost sheets of said stack for inhibiting movement of only said uppermost sheets; said peripheral friction surface comprising an abrasive coating wherein the coefficient of friction between said coating and said top sheet is substantially less than the total coefficient of friction between said coating and said penultimate and lower adjacent sheets whereby said cylindrical member remains stationary during displacement of said top sheet from said stack; and wherein each of said cylindrical members are mounted for quick removability from said support for periodic renewal of its abrasive surface.
 2. The sheet separating apparatus as set forth in claim 16 wherein each of said cylindrical members comprise a cylindrical core receiving a low cost abrasive coated sleeve which may be discarded and replaced for renewal of said abrasive surface.
 3. In combination with apparatus for reproducing visual subject matter on sheet material and having sheet transport means, sheet feeding and separating means for delivering single sheets to said reproducing apparatus comprising: a substantially horizontal shelf supporting a stack of superimposed sheet material adjacent said transport means; sheet movement means disposed above said stack and engaging the top sheet thereof for horizontally displacing said top sheet from said stack and directing it to said transport means; a plurality of normally stationary, cylindrically shaped members having abrasive coatings on the periphery thereof cooperating with the upper portion of said stack for inhibiting movement of the penultimate and lower adjacent sheets during displacement of said top sheet; said cylindrical members comprising an easily removable inner core and an outer abrasive sleeve received by said core; said outer abrasive sleeve being readily removable from said core to facilitate replacement thereof upon the abrasive surface being clogged with said sheet material. 